|Date|Team|Name|Position|Years in NBA|Notes|
|---|---|---|---|---|---|
|April 23, 2009|Houston Rockets|Dikembe Mutombo|C|18|Suffered a season-ending injury|
|May 21, 2009|Free agent|Sam Cassell|G|15|Became an assistant coach of the Wizards|
|September 3, 2009|Free agent|Bruce Bowen|F|12||
|October 22, 2009|Free agent|Mark Madsen|F|9|Became an assistant coach of the Utah Flash (D-League)|
|October 23, 2009|Free agent|Bobby Jackson|G|12||
|October 23, 2009|Free agent|Tyronn Lue|G|11|Became the director of basketball development of the Celtics|
|November 5, 2009|Free agent|Darrick Martin|G|14|Named assistant director of player development of Timberwolves|

Question: how many players retired after playing 12 years?
Answer: 2